Image broadcasting system



March 17, 1936. w. G. H. FINCH IMAGE BROADCASTING SYSTEM Filed Dec. 24. 1934 2 Sheets-Sheet 1 INVENTOR 313% ch ATTORNEY March 17, 1936. i w FINCH I 2,034,015

IMAGE BROADCASTING SYSTEM Filed Dec. .24. 1934 '2 Sheets-Sheet 2 4 I INVENTOR w 6 933$??? ATTORNEY Patented Mar. 17, 1936 UNITED STATES PATENT OFFICE 9 Claims.

The present application which is a continuation in part of my application, Serial No. 717,304,, filed March 26, 1934, relates to facsimile systems and more particularly relates to novel apparatus for and methods of increasing the speed of facsimile transmission.

In the operation of facsimile systems there are many services where details of the image to be transmitted are very unimportant, whereas speed of transmission is extremely important. Thus in the transmission of messages, precision of the letter constructionsis not important so long as the reception is clear. In accordance with my invention, I contemplate sacrificing details of the image and obtaining a corresponding increase in speed of operation.

As is well known in optical systems, there is a maximum degree of image resolution which is determined by the grains of the film on which the record is made. It is, however, possible to obtain cruder, that is to say, less accurately resolved, images, by combining any quantity of these grains of the original film. The result, of course, is merely an averagefor each combined group of these grains, but, as pointed out above, in certain facsimile systems this average sufiices.

In accordance with my invention, I contemplate combining varying areas of the image in producing the facsimile currents for transmission, so that the scanner covers a smaller number of points per line of scanning than would ordinarily be required for that size of image.

Accordingly, an object of my invention is to provide novel apparatus for and methods of reducing scanning periods.

A further object of my invention is to provide a novel construction of scanner whereby the scanner in moving over a smaller path than the line to be scanned still covers the entire line.

Another object of my invention is to provide a composite movement of the scanner at the transmitter and the receiver.

Still another object of my invention is to provide novel apparatus for and methods of adjusting the degree of scanning to fit the desired facsimile conditions.

Another object of my invention is to provide a novelscanner carrying a prism, in which the scanner and the prism are simultaneously operated to cover a wider range of vision than is covered by the movement of the scanneritself.

There are other objects of my invention which, together with the foregoing, will appear in the detailed description of the invention in connection with the drawings whi h is to follow:

pin 64. One end of pin In the drawings:

Figure 1 is a plan view of one form oi. my transmitter.

Figure 2 is a detail from the rear showing my novel construction of producing a composite motion.

Figures 3 and 4 are details of the manner of mounting the scanner prism for producing the composite motion.

Figure 5 is a section of part of the receiver mechanism in which the same scanner movement is obtained. l

Figure 6 is a cross-section of a modified form of my invention.

Figure 7 is a detail of a cam for producing double speed movement of the scanner at the transmitter and receiver.

- Figure l is a top view of the transmitter with portion of it cut away to show the respective posion of the photoelectric cell to'the-platen and the film. I

Upon base 31, the two uprights 38 are securely mounted in any well known manner. The roll of film containing the image to be transmitted is shown at 40 while rollers 42 and 45 are shown in their respective location. The scanning arm II, driven by a synchronous motor through a cam as described in my parent application, is shown in a central position while the optical system, consisting of a source of light impinges light through objective lens, as described in the parent case, on prism 51' mounted upon the scanner in proper location.

Under platen 43, a portion of the photoelectric cell 4 is shown together with suitable mounting means. he photoelectric cell 4 is arcuate'in shape and is supported at its extreme ends in fittings 58 by means of which circuit connections are made from the photoelectric cell to the transmitter. As shown, a slot 59 permits the narrow pencil of rays equal to the thickness of the line and having an opening 63 through which light from the source is admitted to the prism 51. Member 62 at its end 63 forms a bearing for the 64 is provided with a head 65 and the other end with protruding lugs one end I of which is secured to 68 and the other cured to the paper 66 which enter socket 61 in an extension 68 of the support of the prism 51. As will be described hereinafter, pin 64 is free to rock in its bearing 63 and carries with it the prism 51 which is thus rocked about a line at right angles to the line of the path scanned.

Integral with the extension 68 is an arm I0 which carries at its other end a roller 12 shown in Figure 4. Roller I2 rides on a track I3 (Figure 2) secured at its ends to the frame of the apparatus in any well known manner. The roller is kept in engagement with the track by spring I4;

end to the bearing 63.

The arm II is rocked back and forth in the manner described-and shown in detail in my parent application under control of the cammed member I6 (Figure 7). Cammed member 76 has a double carnmed surface as shown so that-arm II is rocked back and forth twice for eachrevolution of the cam 16 but over a smaller arc determined by the curvature of the cammed surface.

As the arm I I travels to the left from its center position shown in Figure 1, prism 51 is carried with it. Since the extension 68 of prism 51 has secured thereto arm III, as the prism is carried to the left, the cam follower I2 riding on the track I3 will rock the member 68 and pin 64 in bearing 63, thus rocking the prism 51.

The track arrangement is such as shown so that the-arm "III and the prism is rocked in a clockwise direction about the bearing when the scanner moves to the left and is rocked in a counterclockwise direction when the scanner is moved to the right. In this manner the normal field of the image covered by the prism is greater than the path of the scanner arm by the angle of movement of the prism. Thus, although the scanner arm may actually cover only one half of the line of the image being scanned, the movement of the prism during this scanner movement covers the remainder of the field of the image. In order to assist in this operation a chopper of the usual construction placed in the line of the light ray will further control the degree of image resolution and will produce a half tone transmitted image.

Figure 5 showsthe receiver employed in my system. In this figure I only show that portion of the receiver which needs to be modified, while the other portion of the mechanism remains unaltered as disclosed in my parent application.

In this modification I place the stylus of the receiver mechanism with a similar member I34 substantially capable of being shaped as shown. I also eliminate the receiving polarized magnet 28 and substitute 'an optical system substantially similar to the one shown in Figure 1 and consisting of a source of light I35 focussed by an objective lens I36 upon prism I31, bending the light through a variable angle as will be described and focussing it upon the light sensitive paper I38 supplied in roll form at I39. After the paper has been exposed, it is fed forward by the same mechanism previously described and the exposed sensitized paper is allowed to accumulate in roll form over takeup rolls I40 pivoted at I4I or may first be passed through a developer and fixer, and then through a dryer after which it is permitted to accumulate on rolls. A groove pulley I42, se-

feed shaft I43 is connected to the takeup groove pulley I44 secured to the takup roller shaft MI, by means of the spring belt I45 which tends to rotate the takeup roller faster than the paper is expelled, thus keeping the paper I38 always taut. The entire receiving mechanism is protected by light-proof casing I45 which protects the device from extraneous sources of light, dust, and grit.

If the paper I38 is coated with a substance which is affected by light proportionate to its intensity, any variation of the light intensityof the source of light I35 will correspondingly produce a variation of intensity of the light beam which strikes the sensitized paper, thus producing an image identical to the one transmitted by the transmitter. I

The mechanism at the receiver for moving the prism I31 although not shown in detail is similar to the transmitter. As at the transmitter, the prism is oscillated as it'is swept back and forth over the field of image thus covering a greater field of the image than would be covered by the actual path of the scanner.

In a modified form for carrying out my invention, I contemplate providing a disc type of scanner having suitable spaced perforations through which light from a source is permitted to pass to the image and the photo cell. mounted to be driven by the motor and placed adjacent the image is provided with a series of perforations spaceda distance from each other such that as one perforation leaves the line of image, the next perforation arranged to cover the next line of the image enters its field.

In accordance with my invention, I contemplate spacing this disc at variable distances from the image and simultaneously replacing the disc with one having a corresponding new spacing of the perforations.

Where the disc is placed in close proximity to the image, the perforations must be spaced 9. distance substantially equal to the line of the image being scanned. If, however, the disc is spaced from the image, the perforation at any one instaIlt encompasses a length of the image line, this length being a function of the distance of the disc from the scanned line.

Accordingly, each perforation will cover the line of the image while passing through'a smaller arc than in the first casedescribed above when the scanner was placed close to the image. Here again, this are is a function of thedistance the scanner is placed from theimage. Therefore, the perforations may be brought closer together and more lines will be scanned for each revolution of the disc than in the first case.

In order to further assist in this a chopper disc similar to that described at the transmitter placed in the path of the light rays will interrupt the light rays during the intervals while the perforation assumes a new position in its rotation covering the next adjacent area to be scanned.

' The same results of :time saving may also be effected by reducing the image to be transmitted to a new image ofsmaller size at the transmitter and enlarging. the received image as described in my parent application of which this is a divi- SlOIl...

In Figure 6 I show another modification of my Such a disc invention in which the stylus is replaced by a pointer I45 ,constantly lightly bearing upon a specially-treated paper I48.

terposed between two diifering polarities of an electrical circuit and I use this principle to record images by utilizing apaper so treated and interpose it between the pointer I45 and the frame I49.

I may preferably conduct the lead in wires to a heating coil on the pointer for producing my discoloration of the chemically treated paper.

.Although for purposes of illustration, I have disclosed preferred embodiments of my invention, it will now be clear that my invention may take other forms and I do not intend to be limited except as set forth in the appended claims.

I claim:

1. In a facsimile system; a record containing an image to'be transmitted; a transmitter scanner comprising a reflecting prism; means \for moving said prism in a scanning movement over a path smaller than the line of said image to be scanned; means for simultaneously rocking said receiver scanner prism in the direction of movement of said scanner while it is moved over said smaller path for shifting its field of image whereby the longer line of the image is scanned as said scanner covers the smaller path; and means for generating picture signals in accordance with the image scanned.

2. In a facsimile system; a record containing an image to be transmitted; a transmitter scanner comprising a reflecting prism; means for moving said prism in a scanning movement over a path smaller than the line of said image to be scanned; means for simultaneously rocking said prism in the direction of movement of said scanner while it is moved over said smaller path for shifting its field of image whereby the longer line of the image is scanned as said scanner covers the smaller path; means for generating picture signals in accordance with the image scanned; a receiver scanner comprising a reflecting prism; means for moving said prism over a path smaller than the line of said image to be scanned; means for simultaneously rocking said prism in the direction of movement of said scanner while it is moved over said smaller path for shifting its field of image whereby the longer line of the image is scanned as said receiver scanner covers the smaller path; and means for operating said in accordance with the picture currents received.

. In a facsimile system; a record containing an image to be transmitted; a transmitter scanner comprising a reflecting prism; means for moving said prism in a scanning movement over a path smaller than the line of said image to be scanned; simultaneously rocking said prism in the direction of movement of said scannerwhile it is moved over said smaller path for shifting its field of image whereby the longer line of the image is scanned as said scanner covers the smaller path; means for generating picture signals in accordance with the image path smaller than the" scanned; a receiver scannercomprising a reflecting prism; means for moving said prism over a line of said image to be scanned; means for-simultaneously rocking said prism in the direction of movement of said scanher being pivoted to each other at a fixed posi-- tion; a track and a track follower connected to said scanner for moving it variably in accordance with the position of saidscanner arm whereby the range of field of said scanner is a function of the movement produced by the scanner arm and of the movement produced by said track and track follower.

5. In a picture transmitting system; a scanner arm; a scanner; said scanner arm and said scanner being pivoted to each other at a fixed position; means connected to said scanner for moving it variably in accordance with the position of said scanner arm whereby the range of field of said scanner is a, function of the movement produced by the scanner arm and of the 7 movement produced by said means.

6. In a picture transmitting system; a scanner arm; a scanner; said scanner arm and said scanner being pivoted to each-other at a fixed position; means connected to said scanner for rocking it in the direction of movement of the scanner arm as said scanner arm from point to point whereby the range of field of said scanner is a function of the movement produced by the scanner arm and of the movement produced by said means.

7. In a picture transmitting system; a scanner arm; a scanner comprising 'a prism, said scanner and scanner arm being pivoted to each 7 other at a fixed position; means connected to said scanner for moving it variably in accordance with the position of said scanner arm whereby the range of field of said scanner is a function of the movement produced by the scanner arm and of the movement produced by said means.

8. In a. picture transmitting system; a scanner arm; a scanner comprising a prism, said scanner and scanner arm being pivoted to each other at a fixed position; a track and atrack follower connected to said scanner for moving it variably in accordance with the position of said scanner arm whereby the range of field of said means. I

WILLIAM G. ii. men. 

